Can you toggle on/off the physical properties of a mesh?
In the physics tab there is an option to set the physics to "Ghost" which is a quick way to disable physics without changing any collision parameters you may have set up.

As for hiding the object, in the Outliner View find your object's listing and click the little eye icon. This disables the rendering of the object in the viewport and in the final render/game.

To make the object reappear and enable its physics again simply toggle the listed options again. :)